TWI597003B - Printed circuit board and method for manufacturing same - Google Patents

Description

Circuit board and manufacturing method thereof

The invention relates to a circuit board and a method of manufacturing the same.

With the development of electronic communication products toward high frequency, high speed and thinness, the industry has higher and higher control requirements for signal transmission loss. At present, an electromagnetic shielding layer is generally disposed on the lower side of the signal line, and the electromagnetic shielding layers on the upper and lower sides are electrically conducted by the rows of conductive through holes to achieve possible electromagnetic interference of the mask. However, due to the gap between the conductive vias, mutual electromagnetic interference exists between the wires in the same layer as the signal lines and the signal lines, so that the signal transmitted by the signal lines is distorted. In addition, the signal transmission electromagnetic field radiates outward, causing the signal transmission rate to be slow.

In view of the above, it is necessary to provide a circuit board and a circuit board manufacturing method capable of solving the above technical problems.

A circuit board comprising a conductive pattern, an upper side photosensitive resin, an upper side conductive material, an upper side mask layer, a lower side photosensitive resin, a lower side conductive material, and a lower side mask layer. The conductive pattern is located in the middle of the thickness direction of the board. The conductive pattern is formed on one side surface of the upper side photosensitive resin. The conductive pattern includes two ground lines and one signal line between the two ground lines. The upper photosensitive resin is provided with two upper trenches corresponding to the two ground lines. The upper side conductive material fills the upper side trench. The upper side mask layer covers the upper side photosensitive resin. The lower photosensitive resin covers the conductive pattern. The lower side photosensitive resin is provided with two lower side grooves corresponding to the two ground lines. The lower side conductive material fills the lower side trench. The lower side mask layer covers the lower side photosensitive material. The upper side mask layer, the upper side conductive material, the ground line, the lower side conductive material and the lower side mask layer enclose a closed mask sleeve. The signal line is located on a central axis of the mask sleeve.

A circuit board manufacturing method comprising the steps of: forming an upper photosensitive resin on one surface of a copper foil; opening two upper trenches in the upper photosensitive resin; forming the copper foil to form a signal line and a conductive pattern of two ground lines, the signal line being located between the two ground lines, the two ground lines respectively corresponding to the two upper side grooves; pressing the lower side photosensitive on the conductive pattern a resin; a plurality of lower trenches respectively corresponding to the two upper trenches are formed in the lower photosensitive resin; and an upper conductive material is filled in the upper trench, respectively, in the lower trench Filling a lower side conductive material, forming an upper side mask layer on the upper side photosensitive resin, and forming a lower side mask layer on the lower side photosensitive resin, the conductive pattern being located at a middle portion in a thickness direction of the circuit board, the upper side The mask layer, the upper conductive material, the ground line, the lower conductive material, and the lower mask layer enclose a closed mask sleeve, the signal line being located on a central axis of the mask sleeve.

Compared with the prior art, the circuit board and the circuit board manufacturing method provided by the present invention are due to the lower side mask layer, the lower side conductive material, the ground line, the upper side conductive material and the upper side mask Forming a closed mask sleeve, and the signal line is located in the mask sleeve, electromagnetic interference between other wires of the conductive pattern and the signal line, and electromagnetic field of the signal transmission are concentrated Inside the cover sleeve to increase the signal transfer rate.

1 is a schematic cross-sectional view of a copper foil provided by an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing the upper side photosensitive resin formed on one surface of the copper foil of Fig. 1.

Fig. 3 is a schematic cross-sectional view showing the upper side groove formed in the upper photosensitive resin of Fig. 2;

Fig. 4 is a schematic cross-sectional view showing the formation of a conductive pattern by forming the copper foil of Fig. 3.

Fig. 5 is a schematic cross-sectional view showing the lower side photosensitive resin laminated on the conductive pattern of Fig. 4.

Fig. 6 is a schematic cross-sectional view showing the lower side groove formed in the lower photosensitive resin of Fig. 5;

7 is a top side conductive material filled in the upper side trench of FIG. 6, and a lower side conductive material in the lower side trench, respectively, and an upper side mask layer is formed on the upper side photosensitive resin and a lower side mask layer is formed on the lower side photosensitive resin, respectively. Schematic diagram of the profile behind the layer.

8 is a schematic cross-sectional view showing an upper protective layer formed on the upper mask layer of FIG. 7 and a lower protective layer formed on the lower mask layer, respectively.

The circuit board and the circuit board manufacturing method provided by the present invention are further described below in conjunction with specific embodiments.

A method of fabricating a circuit board provided by a specific embodiment of the present invention includes the following steps.

In the first step, referring to Figure 1, a copper foil 10 is provided.

In the present embodiment, the copper foil 10 has a sheet shape. The copper foil 10 can be cut by cutting the raw material of the rolled copper foil according to specific needs.

In the second step, referring to FIG. 2, the upper side photosensitive resin 20 is formed on one surface of the copper foil 10.

In the third step, referring to FIG. 3, the upper side trench 21 is opened in the upper side photosensitive resin 20.

In the present embodiment, two upper grooves 21 are formed in the upper photosensitive resin 20. In the present embodiment, the upper side grooves 21 are opened from the surface of the upper side photosensitive resin 20 facing away from the copper foil 10 toward the upper side photosensitive resin 20. The two upper side grooves 21 extend in the same direction (all perpendicular to the inside of the figure) and are parallel to each other. Each of the upper side grooves 21 penetrates the upper side photosensitive resin 20. A part of the copper foil 10 is exposed from each of the upper side grooves 21. In this embodiment, the upper side groove 21 has an inverted trapezoidal cross section perpendicular to the extending direction thereof. The groove width of the upper side groove 21 gradually decreases from the surface of the upper side photosensitive resin 20 facing away from the copper foil 10 toward the copper foil 10. The upper side trench 21 can be formed by exposure development.

In the fourth step, referring to FIG. 4, the copper foil 10 is formed to form a conductive pattern 30.

In the embodiment, the conductive pattern 30 includes one signal line 31, two ground lines 32, and a plurality of wires 33. The signal line 31 is located between the two ground lines 32. The two ground lines 32 space the plurality of wires 33 from the signal line 31. The gap of the conductive pattern 30 exposes a portion of the upper side photosensitive resin 20.

In the present embodiment, the extending direction of the signal line 31 and the ground line 32 coincides with the extending direction of the upper trench 21 . Each of the ground lines 32 corresponds to one of the upper trenches 21. In the present embodiment, the signal line 31 and the ground line 32 are parallel to each other. The signal lines 31 are spaced apart from each of the ground lines 32 by the same distance.

In this embodiment, the conductive pattern 30 can be formed by etching.

In the fifth step, referring to FIG. 5, the lower side photosensitive resin 40 is pressed on the conductive pattern 30.

The lower side photosensitive resin 40 covers the conductive pattern 30. The lower side photosensitive resin 40 fills the gap of the conductive pattern 30, and is bonded to the upper side photosensitive resin 20 to form a dielectric layer 41. The conductive pattern 30 is located on a center line in the thickness direction of the dielectric layer 41. The conductive pattern 30 is symmetrical in its thickness direction with respect to a center line of the thickness direction of the dielectric layer 41.

In the sixth step, referring to FIG. 6, the lower side trench 42 is opened in the lower side photosensitive resin 40.

In the present embodiment, two lower grooves 42 are formed in the lower photosensitive resin 40. The opening direction of the lower side groove 42 is opposite to the opening direction of the upper side groove 21. In the present embodiment, the lower side groove 42 is opened from the surface of the lower side photosensitive resin 40 facing away from the conductive pattern 30 toward the lower side photosensitive resin 40. Each of the lower side grooves 42 penetrates the lower side photosensitive resin 40. The extending direction of the two lower side trenches 42 coincides with the extending direction of the two grounding lines 32. Each of the lower side trenches 42 corresponds to a ground line 32. Each of the ground lines 32 is exposed from a corresponding lower side trench 42. Each of the lower side grooves 42 also corresponds to one of the upper side grooves 21. The offset tolerance between each of the lower side trenches 42 and its corresponding upper side trench 21 is less than or equal to 75 microns. In this embodiment, the cross section of the lower side trench 42 perpendicular to the extending direction thereof is trapezoidal. The groove width of the lower side groove 42 gradually decreases from the surface of the lower side photosensitive resin 40 away from the conductive pattern 30 toward the conductive pattern 30. The groove width decreasing direction of the lower side groove 42 is opposite to the groove width decreasing direction of the upper side groove 21. The lower side trench 42 can be formed by exposure development.

In the seventh step, referring to FIG. 7, the upper side trench 21 is filled with the upper side conductive material 51 and the lower side trench 42 is filled with the lower side conductive material 52; and the upper side photosensitive resin 20 is formed on the upper side. The mask layer 61 and the lower mask layer 62 are formed on the lower side photosensitive resin 40.

The upper conductive material 51 fills the upper trench 21 . The upper side mask layer 61 covers the upper side photosensitive resin 20. The upper side mask layer 61 is electrically connected to the upper side conductive material 51. In the present embodiment, the upper conductive material 51 is formed simultaneously with the upper mask layer 61. In the embodiment, the upper conductive material 51 includes a seed layer 511 and a plating layer 512. The seed layer 511 is formed on the surface of the upper side trench 21. The plating layer 512 is formed on the surface of the seed layer 511 and fills the upper trench 21 . The upper mask layer 61 includes a seed layer 611 and a plating layer 612. The seed layer 611 is formed on the surface of the upper side photosensitive resin 20. The plating layer 612 is formed on the surface of the seed layer 611. In the present embodiment, the seed layers 511, 611 are simultaneously formed and have an integral structure. The plating layers 512, 612 are simultaneously formed and are of unitary construction.

The lower side conductive material 52 fills the lower side trenches 42. The lower side mask layer 62 covers the lower side photosensitive resin 40. The lower side mask layer 62 is electrically connected to the lower side conductive material 52. In the present embodiment, the lower conductive material 52 is formed simultaneously with the lower mask layer 62. In the embodiment, the lower conductive material 52 includes a seed layer 521 and a plating layer 522. The seed layer 521 is formed on the surface of the lower side trench 42. The plating layer 522 is formed on the surface of the seed layer 521 and fills the lower trench 42. The lower mask layer 62 includes a seed layer 621 and a plating layer 622. The seed layer 621 is formed on the surface of the lower side photosensitive resin 40. The plating layer 622 is formed on the surface of the seed layer 621. In the present embodiment, the seed layers 521, 621 are simultaneously formed and have an integral structure. The plating layers 522, 622 are simultaneously formed and are of unitary construction.

In the present embodiment, the upper mask layer 61 and the lower mask layer 62 have the same thickness.

The lower mask layer 62, the lower side conductive material 52, the ground line 32, the upper side conductive material 51 and the upper side mask layer 61 enclose a closed mask sleeve 70. The signal line 31 is located in the mask sleeve 70 to avoid electromagnetic interference between the wire 33 and the signal line 31, and at the same time, the signal transmission electromagnetic field is concentrated in the mask sleeve, thereby improving signal transmission. rate. In this embodiment, the signal line 31 is located on the central axis of the mask sleeve 70 to further enhance the electromagnetic mask effect and increase the signal transmission rate.

In the present embodiment, the upper conductive material 51, the upper mask layer 61, the lower conductive material 52, and the lower mask layer 62 can be formed as follows.

First, a seed layer 511 is formed on the surface of the upper trench 21. A seed layer 611 is formed on the surface of the upper side photosensitive resin 20. A seed layer 521 is formed on the surface of the lower trench 42. A seed layer 621 is formed on the surface of the lower side photosensitive resin 40. The seed layers 511, 611, 521, and 621 can be formed by electroless plating such as electroless plating, vapor deposition, sputtering, or the like.

Next, a plating layer 512 is formed on the surface of the seed layer 511. The plating layer 512 fills the upper trench 21 . A plating layer 612 is formed on the surface of the seed layer 611 by electroplating. A plating layer 522 is formed on the surface of the seed layer 521 by electroplating. The plating layer 522 fills the lower side trenches 42. A plating layer 622 is formed on the surface of the seed layer 621 by electroplating.

In other embodiments, the upper conductive material 51 and the upper mask layer 61, the lower mask layer 62 and the lower mask layer 62 may be formed at different times. At this time, first, the conductive material 51, 52 is filled in the upper trench 21 and the lower trench 42, respectively; then, the surface of the conductive material in the upper photosensitive resin 20 and the upper trench 21, respectively, is sensitized on the lower side. A surface layer is formed on the surface of the resin 40 and the surface of the conductive material in the lower trench 42. Finally, a plating layer is formed on the surface of the seed layer to form an upper mask layer 61 and a lower mask layer 62.

In the eighth step, referring to FIG. 8, an upper side protective layer 81 is formed on the surface of the upper side mask layer 61; and a lower side protective layer 82 is formed on the surface of the lower side mask layer 62.

The upper side protective layer 81 covers the upper side mask layer 61. The lower side mask layer 62 covers the lower side mask layer 62. In the present embodiment, the thickness of the upper protective layer 81 is the same as the thickness of the lower protective layer 82.

It can be understood that in other embodiments, the upper protective layer 81 and the lower protective layer 82 may not be formed.

A specific embodiment of the present invention also provides a circuit board 100. The circuit board 100 can be fabricated by the above-described circuit board manufacturing method.

Referring to FIG. 8 again, the circuit board 100 includes a conductive pattern 30, an upper side photosensitive resin 20, an upper side conductive material 51, an upper side mask layer 61, an upper side protective layer 81, a lower side photosensitive resin 40, a lower side conductive material 52, and a lower layer. Side mask layer 62 and lower side protective layer 82.

The conductive pattern 30 is located in the middle of the thickness direction of the circuit board 100. In the embodiment, the conductive pattern 30 includes one signal line 31, two ground lines 32, and a plurality of wires 33. The signal line 31 is located between the two ground lines 32. The wire 33 is located outside the two ground wires 32 with respect to the signal line 31. In the present embodiment, the signal lines 31 and the ground lines 32 extend in the same direction (both perpendicular to the inside of the figure). The signal line 31 and the ground line 32 are parallel to each other. The signal lines 31 are spaced apart from each of the ground lines 32 by the same distance.

The upper side photosensitive resin 20 is formed on the lower side photosensitive resin 40. The upper photosensitive resin 20 covers the conductive pattern 30. An upper side groove 21 is opened in the upper photosensitive resin 20. In the present embodiment, the upper photosensitive resin 20 is provided with two upper grooves 21 . The two upper trenches 21 extend in a direction that coincides with the extending direction of the ground line 32. Each of the upper trenches 21 corresponds to one of the ground lines 32. Each of the upper side grooves 21 penetrates the upper side photosensitive resin 20, and a corresponding ground line 32 thereof is exposed from the upper side groove 21. In this embodiment, the upper side groove 21 has an inverted trapezoidal cross section perpendicular to the extending direction thereof. The groove width of the upper side groove 21 gradually decreases from the surface of the upper side photosensitive resin 20 facing away from the conductive pattern 30 toward the conductive pattern 30.

The upper conductive material 51 fills the upper trench 21 . In the embodiment, the upper conductive material 51 includes a seed layer 511 and a plating layer 512. The seed layer 511 is formed on the surface of the upper side trench 21. The plating layer 512 is formed on the surface of the seed layer 511 and fills the upper trench 21 .

The upper side mask layer 61 covers the upper side photosensitive resin 20 and is electrically connected to the upper side conductive material 51. The upper mask layer 61 includes a seed layer 611 and a plating layer 612. The seed layer 611 is formed on the surface of the upper side photosensitive resin 20. The plating layer 612 is formed on the surface of the seed layer 611. In the present embodiment, the seed layers 611 and 511 have an integral structure. The plating layers 612, 512 are of unitary construction.

The upper side protective layer 81 covers the upper side mask layer 61.

The lower side photosensitive resin 40 covers the conductive pattern 30, fills a gap of the conductive pattern 30, and is bonded to the upper side photosensitive resin 20 to form a dielectric layer 41. The conductive pattern 30 is located on a center line in the thickness direction of the dielectric layer 41. The conductive pattern 30 is symmetrical in its thickness direction with respect to a center line of the thickness direction of the dielectric layer 41. The lower side photosensitive resin 40 is provided with a lower side groove 42 corresponding to the ground line 32. In the present embodiment, the lower side photosensitive resin 40 is provided with two lower side grooves 42. Each of the lower side grooves 42 penetrates the lower side photosensitive resin 40. The extending direction of the two lower side trenches 42 coincides with the extending direction of the two grounding lines 32. Each of the lower side trenches 42 corresponds to a ground line 32. Each of the lower side trenches 42 exposes its corresponding ground line 32. Each of the lower side grooves 42 also corresponds to one of the upper side grooves 21. The offset tolerance between each of the lower side trenches 42 and its corresponding upper side trench 21 is less than or equal to 75 microns. In this embodiment, the cross section of the lower side trench 42 perpendicular to the extending direction thereof is trapezoidal. The groove width of the lower side groove 42 gradually decreases from the surface of the lower side photosensitive resin 40 away from the conductive pattern 30 toward the conductive pattern 30. The groove width decreasing direction of the lower side groove 42 is opposite to the groove width decreasing direction of the upper side groove 21.

The lower side conductive material 52 fills the lower side trenches 42. In the embodiment, the lower conductive material 52 includes a seed layer 521 and a plating layer 522. The seed layer 521 is formed on the surface of the lower side trench 42. The plating layer 522 is formed on the surface of the seed layer 521 and fills the lower trench 42.

The lower side mask layer 62 covers the lower side photosensitive resin 40 and is electrically connected to the lower side conductive material 52. In the embodiment, the lower mask layer 62 includes a seed layer 621 and a plating layer 622. The seed layer 621 is formed on the surface of the lower side photosensitive resin 40. The plating layer 622 is formed on the surface of the seed layer 621. In the present embodiment, the seed layers 521 and 621 have an integral structure. The plating layers 522, 622 are of unitary construction. The thickness of the lower mask layer 62 is the same as the thickness of the upper mask layer 61.

The lower side protective layer 82 covers the lower side mask layer 62. The thickness of the lower side protective layer 82 is the same as the thickness of the upper side protective layer 81.

The lower mask layer 62, the lower side conductive material 52, the ground line 32, the upper side conductive material 51 and the upper side mask layer 61 enclose a closed mask sleeve 70. The signal line 31 is located in the mask sleeve 70 to avoid electromagnetic interference between the wire 33 and the signal line 31, and at the same time, the signal transmission electromagnetic field is concentrated in the mask sleeve, thereby improving signal transmission. rate. In this embodiment, the signal line 31 is located on the central axis of the mask sleeve 70 to further enhance the electromagnetic mask effect and increase the signal transmission rate.

It can be understood that, in other embodiments, the circuit board 100 may not include the upper protective layer 81 and the lower protective layer 82.

Compared with the prior art, the circuit board and the circuit board manufacturing method provided by the present invention are due to the lower side mask layer, the lower side conductive material, the ground line, the upper side conductive material and the upper side mask Forming a closed mask sleeve, and the signal line is located in the mask sleeve, electromagnetic interference between other wires of the conductive pattern and the signal line, and electromagnetic field of the signal transmission are concentrated Inside the cover sleeve to increase the signal transfer rate.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only for the preferred embodiment of the present invention and the data listed therein are used for testing and reference, and the scope of patent application in this case cannot be limited thereby. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

Board: 100

Copper foil: 10

Upper side photosensitive resin: 20

Upper side groove: 21

Conductive graphic: 30

Signal line: 31

Ground wire: 32

Wire: 33

Lower side photosensitive resin: 40

Dielectric layer: 41

Lower groove: 42

Upper conductive material: 51

Lower conductive material: 52

Upper mask layer: 61

Lower mask layer: 62

Seed layer: 511, 521, 611, 621

Plating layer: 512, 522, 612, 622

Mask sleeve: 70

Upper protective layer: 81

Lower protective layer: 82

no

Board: 100

Upper side photosensitive resin: 20

Upper side groove: 21

Conductive graphic: 30

Signal line: 31

Ground wire: 32

Wire: 33

Lower side photosensitive resin: 40

Dielectric layer: 41

Lower groove: 42

Upper conductive material: 51

Lower conductive material: 52

Upper mask layer: 61

Lower mask layer: 62

Seed layer: 511, 521, 611, 621

Plating layer: 512, 522, 612, 622

Mask sleeve: 70

Upper protective layer: 81

Lower protective layer: 82

Claims (9)

A circuit board manufacturing method includes the steps of:
Forming the upper photosensitive resin on one side surface of a copper foil;
Opening two upper trenches in the upper photosensitive resin;
Forming the copper foil into a conductive pattern including a signal line and two ground lines, wherein the signal line is located between the two ground lines, and the two ground lines respectively correspond to the two upper side trenches ;
Pressing the lower side photosensitive resin on the side of the conductive pattern facing away from the upper side photosensitive resin;
Two lower trenches respectively corresponding to the two upper trenches are formed in the lower photosensitive resin; and an upper conductive material is filled in the upper trench, respectively, and the lower trench is filled in the lower trench a lower side conductive material, an upper side mask layer is formed on the upper side photosensitive resin, and a lower side mask layer is formed on the lower side photosensitive resin to form the circuit board;
Wherein the conductive pattern is located in a middle portion of the thickness direction of the circuit board, and the upper side mask layer, the upper side conductive material, the ground line, the lower side conductive material and the lower side mask layer enclose a closed mask sleeve. The signal line is located on the central axis of the mask sleeve. The method of fabricating a circuit board according to claim 1, wherein the method for fabricating the circuit board further comprises: forming an upper side protective layer on a surface of the upper side mask layer and a lower side protective layer on a surface of the lower side mask layer; step. The method of fabricating a circuit board according to claim 1, wherein an upper conductive material is filled in the upper trench, a lower conductive material is filled in the lower trench, and a photoresist is formed on the upper photosensitive resin. The upper side mask layer and the lower side mask layer on the lower side photosensitive resin include:
Forming a seed layer on the upper trench surface, the upper photosensitive resin surface, the lower trench surface, and the lower photosensitive resin surface;
Forming a plating layer on the seed layer of the upper trench surface, the upper photosensitive resin surface, the lower trench surface, and the lower photosensitive resin surface, the plating layer filling the upper trench and the lower trench respectively a groove and extending a seed layer covering the upper photosensitive resin surface and the lower photosensitive resin surface. The method of fabricating a circuit board according to claim 1, wherein the upper side trench is opposite to the opening direction of the lower side trench. A circuit board comprising a conductive pattern, an upper side photosensitive resin, an upper side conductive material, an upper side mask layer, a lower side photosensitive resin, a lower side conductive material and a lower side mask layer, wherein the conductive pattern is located in the middle of the thickness direction of the circuit board The conductive pattern is formed on one side surface of the upper photosensitive resin, the conductive pattern includes two ground lines and one signal line between the two ground lines, and the upper side photosensitive resin corresponds to the two grounds The line is provided with two upper side trenches, the upper side conductive material fills the upper side trench, the upper side mask layer covers the upper side photosensitive resin, and the lower side photosensitive resin covers the conductive pattern, the lower side The side photosensitive resin is provided with two lower side grooves corresponding to the two ground lines, the lower side conductive material fills the lower side groove, and the lower side mask layer covers the lower side photosensitive material, the upper side The mask layer, the upper conductive material, the ground line, the lower conductive material, and the lower mask layer enclose a closed mask sleeve, the signal line being located on a central axis of the mask sleeve. The circuit board of claim 5, wherein the circuit board further comprises an upper side protective layer and a lower side protective layer, the upper side protective layer covering the upper side mask layer, and the lower side protective layer covering the lower layer Side mask layer. The circuit board of claim 5, wherein each of the lower side trenches corresponds to one of the upper side trenches, and a offset tolerance between the lower side trenches and its corresponding upper side trenches is less than 75 micrometers. The circuit board of claim 5, wherein a groove width of the upper side groove gradually decreases from the surface of the upper side photosensitive resin facing away from the conductive pattern toward the conductive pattern, and a groove width of the lower side groove The conductive pattern gradually decreases from a surface of the lower photosensitive resin facing away from the conductive pattern. The circuit board of claim 5, wherein the conductive pattern further comprises a plurality of wires, the two ground wires spacing the plurality of wires from the signal line.